1. Field of the Invention
The present invention relates to an image composition apparatus, an image composition method, and a program in which an influence of a sudden pixel defect is eliminated in compositing a plurality of pieces of image data.
2. Description of Related Art
Recently, various image composition apparatuses for compositing images of a plurality of pieces of image data are proposed such as an image pickup apparatus which acquires a plurality of pieces of image data at a predetermined time interval and accumulates and adds/composites the plurality of pieces of image data so that a photographed image is monitored during bulb photographing (see Japanese Patent Laid-Open No. 2005-117395 (hereinafter referred to as Patent Literature 1), for example), an image composition apparatus in which brightness of each pixel of the plurality of pieces of image data is compared, the brightness of the pixel with a high brightness level is selected, and image composition is performed (see Japanese Patent No. 4148586 (hereinafter referred to as Patent Literature 2), for example) and the like.
There is a defective pixel in an image pickup element, and a bright point or a black point remains in the image at a position of the defective pixel regardless of an object. The defective pixels are not limited to the pixels in which defects occur at all times but include a defective pixel in which a defect does not occur at all times but suddenly occurs.
Various technologies for eliminating an influence of such defective pixels have been proposed. For example, in an image composition apparatus disclosed in Japanese Patent Laid-Open No. 2004-056395 (hereinafter referred to as Patent Literature 3), a plurality of images is photographed, and a position of a suddenly occurring defective pixel (defective pixel which does not occur at all times) is detected from these plurality of images and recorded in a memory. An image composition apparatus disclosed in Japanese Patent No. 4349207 (hereinafter referred to as Patent Literature 4) uses a previous frame image, calculates an average value of those in the same color and adjacent to a pixel of interest, compares it using a threshold value, and corrects/calculate a level of the pixel of interest on the basis of this comparison result.